MULTIPLE CHOICE.  Choose the one alternative that best completes the statement or answers the question.

1)  A kilogram is a measure of an object's

A) weight.

B) force.

C) mass.

D) gravity.

E) center of mass.

B) the gravitational attraction between you and the earth.

C) a property of mechanical equilibrium.

D) all of these.

E) none of these.

3)  Compared to the mass of a certain object on earth, the mass of the same object on the moon is

A) less. B)  more. C)  the same.

4)  A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding at constant velocity is

A) zero newtons.

B) equal to the weight of the puck.

C) the weight of the puck divided by the mass of the puck.

D) the mass of the puck multiplied by 9.8 meters per second per second.

E) none of these.

5)  An object's weight may properly be expressed in

A) meters per second. B)  kilograms.

C) newtons. D)  none of the above.

6)  A 10-kg brick and a 1-kg book are dropped in a vacuum. The force of gravity on the 10-kg brick is

A) the same as the force on the 1-kg book.

B) 10 times as much as the force on the 1-kg book.

C) zero.

7)  If an object's mass is decreasing while a constant force is applied to the object, the acceleration

A) decreases. B)  increases. C)  remains the same.

8)  An object is pulled northward with a force of 10 N and southward with a force of 15 N.  The magnitude of the net force on the object is

A) 0 N.

B) 5 N.

C) 10 N.

D) 15 N.

E) none of these.

9)  Which has zero acceleration?  An object

A) at rest.

B) moving at constant velocity.

C) in mechanical equilibrium.

D) all of these.

E) none of these.

10)  Hang from a pair of gym rings and the upward support forces of the rings will always

A) each be half your weight.

B) each be equal to your weight.

11)  When a falling object has reached its terminal velocity, its acceleration is

A) constant. B)  zero. C)  g.

12)  A skydiver, who weighs 500 N, reaches terminal velocity of 90 km/h.  The air resistance on the diver is then

A) 90 N.

B) 250 N.

C) 410 N.

D) 500 N.

E) none of these.

13)  A 500-N parachutist opens his chute and experiences an air resistance force of 800 N.  The net force on the parachutist is

A) 300 N downward.

B) 500 N downward.

C) 800 N downward.

D) 300 N upward.

E) 500 N upward.

14)  A falling skydiver of mass 100 kg experiences 500 N air resistance.  The acceleration of the skydiver is

A) 0.2 g.

B) 0.3 g.

C) 0.4 g.

D) 0.5 g.

E) more than 0.5 g.

15)  The two measurements necessary for calculating average speed are

A) acceleration and time.

B) velocity and time.

C) distance and time.

D) distance and acceleration.

E) velocity and distance.

16)  What is the acceleration of a car that maintains a constant velocity of 100 km/h for 10 seconds?

A) 0. B)  10 km/h/s. C)  10 m/h/s. D)  1000 km/h/s.

17)  The gain in speed each second for a freely-falling object is about

A) 0.

B) 5 m/s.

C) 10 m/s.

D) 20 m/s.

E) depends on the initial speed.

18)  Ten seconds after starting from rest, a freely-falling object will have a speed of about

A) 10 m/s. B)  50 m/s.

C) 100 m/s. D)  more than 100 m/s

19)  If a baseball being thrown goes from zero to 30 m/s in 0.1 second, what is its average acceleration?

A) 3 m/s/s

B) 30 m/s/s

C) 300 m/s/s

D) 3000 m/s/s

E) none of these

20)  Drop a rock from a 5-m height and it accelerates at 10 m/s/s and strikes the ground 1 s later. Drop the same rock from a height of 2.5 m and its acceleration of fall is

A) about half. B)  the same. C)  more.

21)  A ball is thrown upwards and caught when it comes back down. Neglecting air resistance, its speed when caught is

A) more than the speed it had when thrown upwards.

B) less than the speed it had when thrown upwards.

C) the same as the speed it had when thrown upwards.

22)  At one instant an object in free fall is moving downward at 50 meters per second.  One second later its speed is about

A) 25 m/s. B)  50 m/s. C)  55 m/s. D)  60 m/s. E)  100 m/s.

23)  When a rock thrown straight upwards gets to the exact top of its path, its

A) velocity is zero and its acceleration is zero.

B) velocity is zero and its acceleration is about 10 meters per second per second.

C) velocity is about 10 m/s and its acceleration is zero.

D) velocity is about 10 m/s and its acceleration is about 10 meters per second per second.

E) none of these.